175
FXUS21 KWNC 311847
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT August 31 2026

SYNOPSIS: Broad mid-level ridging is forecast to linger across the central
contiguous U.S. (CONUS) from the end of week-1 into week-2 favoring a
continuation of anomalous warmth and extreme heat centered across portions of
the Great Plains and Mississippi Valley at the beginning of the period. The
abnormally hot and dry conditions over the past few weeks are expected to
continue through much of week-2, supporting a Rapid Onset Drought (ROD) risk
for portions of the Central and Southern Plains and the Middle and Lower
Mississippi Valley. Some areas have been removed in ROD across parts of Texas
and Louisiana due to anticipated rainfall during week-1. Increased potential of
Tropical cyclone activity in the East Pacific may support a surge of moisture
into the western CONUS, supporting a slight risk of heavy precipitation across
the Four Corner region.

HAZARDS

Moderate risk of extreme heat for parts of the Central and Southern Plains, and
Middle and Lower Mississippi Valley, Tue-Wed, Sep 8-9.

Slight risk of extreme heat for parts of the Desert Southwest, central and
east-central CONUS, Tue-Mon, Sep 8-14.

Slight risk of heavy precipitation across parts of the Great Basin, Central and
Southern Rockies, southern California, and Southwest, Tue-Sat, Aug 8-12.

Rapid Onset Drought (ROD) risk for portions of the Central and Southern Plains
and the Middle and Lower Mississippi Valley.

DETAILED SUMMARY

FOR THURSDAY SEPTEMBER 03 - MONDAY SEPTEMBER 07:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY SEPTEMBER 08 - MONDAY SEPTEMBER 14: The 0z ECENS, GEFS, and
Canadian ensembles continue to have good agreement indicating mid-level ridging
lingering across the south-central CONUS at the start of week-2, with
significant uncertainty thereafter regarding the evolution of the ridge. The
ECENS ensemble shows the greatest amplitude relative to the GEFS and CMCE,
depicting a 596-dm high centered over northern Texas at the start of the
period, translating to the ECENS having higher probabilities of heat than its
counterparts. This pattern supports a continuation of anomalously warm
temperatures (upwards of +10 deg F above normal) across the Central and
Southern Plains and adjacent areas of the Mississippi Valley. A moderate risk
(40-60% chance) of extreme heat remains designated for these areas where the
GEFS and ECMWF Probabilistic Extremes Tools (PETs) continue to indicate at
least a 40% chance of maximum temperatures exceeding the 90th percentile
climatologically and where actual temperatures or heat index values exceed 105
deg F (110 deg F in the more humid areas of southern Texas). The National Blend
of Models show the potential for some locations in the Southern Plains reaching
or exceeding record breaking high temperatures. The slight risk (20-40% chance)
continues through Sep 11 and extends throughout much of the Midwest, and also
into the Southeast. The ECENS mean favors the ridge shifting and expanding
westward throughout the period with troughing developing across the
northeastern CONUS, whereas the GEFS and CMCE expands the ridging eastward with
more troughing across the Northwest. These differences translate to uncertainty
regarding where and how the heat hazard evolves.



The continued extreme heat risks during week-2 are likely being reinforced by
feedback processes associated with rapidly drying soils and drought within many
of the highlighted regions. The hot and dry conditions favored are also
expected to elevate the risk of fire weather conditions during the period.
Rapid Onset Drought (ROD) risk is designated across portions of the Central and
Southern Plains and Middle and Lower Mississippi Valley. This area has
registered 30- to 45-day precipitation deficits greater than 2 inches below
normal and/or under half of normal, with less than an inch expected during the
next two weeks. Some southern periphery areas are removed across southeastern
Texas and southern Louisiana due to Tropical Depression 5 in the Gulf being
monitored by the National Hurricane Center (NHC) that may bring precipitation
to portions of the Gulf Coast.



Across the eastern and central Pacific, there has been a pronounced uptick in
tropical activity during the past week. Tropical Storms Karina and Lowell are
located near 120 deg W and 145 deg W respectively. The National Hurricane
Center (NHC) analyzes  Karina as a  major hurricane as it tracks
west-northwestward. Karina along with a potential additional area highlighted
with a high chance (90%) of tropical cyclone formation offshore of southwestern
Mexico as of 11am PDT could lead to a renewed Gulf surge event at the end of
week-1 into week-2. Therefore a slight risk of heavy precipitation for  parts
of the Great Basin, Central and Southern Rockies, southern California, and
Southwest, Aug 8-12, where there is at least a 40-50% chance of above-normal
precipitation during week-2 and enhanced precipitation indicated by various
guidance tools. Localized flooding is possible as always with increased
potential of enhanced rainfall due to thunderstorms. Additionally, although
there is ample uncertainty associated with this disturbance, heavy
precipitation, high winds, and other adverse impacts to Hawaii cannot be ruled
out during week-2, with both the GEFS and ECMWF PETS depicting at least a 20
percent chance of 3-day precipitation values exceeding the 85th climatological
percentile across the state.



In the Atlantic, Tropical Storm Dolly has opened up into a wave. There is some
potential albeit fairly low for some redevelopment during the next few days as
this system reaches the southeastern Gulf of America. While unlikely to be a
significant system, there could be periods of local enhanced rainfall across
parts of Florida and the Southeast lingering from the end of week-1 into the
start of week-2, although much of it seems to likely time out prior to this
period.



Enhanced onshore flow may bring periods of heavy precipitation and gusty winds
across southern Alaska late in week-1 into the start of week-2, with much of
the impacts anticipated to time out by week-2. Snow cannot be ruled out across
portions of the Brooks Range and the higher elevations of southeastern Alaska.

FORECASTER: Melissa Ou

$$